Caloric restriction (CR: reducing caloric intake 30-40 percent below ad libitum levels) has been repeatedly shown to extend lifespan, reduce the incidence and delay the onset of age-related disease, enhance stress protection, and attenuate functional decline in mammals. The NIA longitudinal study of CR and aging in rhesus monkeys is in its 32nd year and 16% of the animals remain on study. In 2012, we reported findings of improved health; however, unlike findings from a similar study at the University of Wisconsin, the NIA CR monkeys did not have improved survival compared to the controls. In 2017, we compared the study designs and outcomes concluding that aging is malleable in primates and a reasonable target for intervention. Both studies are on-going, and we will continue to monitor the monkeys for age-related changes in many health parameters. Monkeys are currently tested on learning and memory tasks. Additionally, tissue and serum are used to assess biomarkers of aging.